JSFiddle - React, Tailwind, and code Playground

HTML

<div id="cont"></div>
<div class="snake"></div>

CSS

#cont {
    width: 150px;
    height: 150px;
    background: #000;
    margin: 10px;
}
.snake {
    width: 5px;
    height: 5px;        
    background: #f00;
    position: absolute;
    top: 5px;
    left: 15px;
    animation: around 5s infinite;
    -webkit-animation: around 5s infinite;
}
@keyframes around
{
    0% { left: 15px; top: 5px; }
    25% { left: 165px; top: 5px;  }
    50% { top:  160px; left: 165px; }
    75% { left: 15px; top: 160px; }
    100% { top: 5px; left: 15px; }
}
@-webkit-keyframes around
{
    0% { left: 15px; top: 5px; }
    25% { left: 165px; top: 5px;  }
    50% { top:  160px; left: 165px; }
    75% { left: 15px; top: 160px; }
    100% { top: 5px; left: 15px; }
}